Tuner



July 3l, 1956 J. A. KOSTRIZ'A ETAL TUNER Filed Jan. l2, 1953 United States Patent O TUNER John A. Kostriza, New Dorp, and Paul Terranova, Brook- N lyn, N. Y., assignors to International Telephone and Telegraph Corporation, a corporation of Maryland This invention relates to tuners for microwave transmission lines and more particularly to tuners and combinations of tuners for use in conjunction with the lineabove-ground type of transmission line.

In the patent to D. D. Grieg and H. F. Engelmann, No. 2,721,312 and the copending application of M. Arditi and P. Parzen, Serial No. 286,764, tiled May 8, 1952, microwave transmission lines comprising generally a line-above-ground type of transmission line, over which microwave energy may be propagated in a mode simulating a TEM mode, are shown. In this type of trans* mission line, a planar conductor is employedV as a ground conductor with a line conductor disposed in spaced parallel relation thereto by means of a strip or layer of dielectric material. The line and planar conductors are preferably of different widths, that is, the planar conductor is made wider than the line conductor so that it appears as an infinite conducting surface to the line conductor, thereby insuring an electric field distribution characterized generally by the TEM mode. For example, the field distribution is believed to be similar to that which occurs between one of the conductors of a truly parallel conductor system and the neutral plane between such conductors. The important parameters of this type of transmission lane are the width of the line conductor and the dielectricvspacing between the line and planar conductors.

One of the objects of this invention is to provide a tuner for use in conjunction with a microwave transmission line of the character described above; and a further object is to provide a combination of such tuners arranged in tandem along the transmission line as a band pass lter.

One of the features of this invention is the employment of transmission line material of the character employed in the line-aboVe-ground type of transmission line to form a resonant network in association with the transmission line. The tuners, in fact, employ as part of the network the conductors of the transmission line with which it is associated. This is accomplished by the provision of two network conductors disposed at spaced points along the line conductor and in parallel spaced relation to the ground conductor. Another network conductor couples the two network conductors at an adjustable distance with respect to the line conductor to thereby determine the resonant characteristics of the network. As a further feature of the invention, the three network conductors are arranged as a unit for adjustment lengthwise along the transmission line, so that where a plurality Vof such tuners are employed at spaced points along the line the spacing therebetween may be adjusted. A further feature is the adaptability of this type of tuner and transmission line to printed circuit technique since the conductors thereof may be formed simultaneously by an etching process on strips or layers of dielectric material.

The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent by reference to the following description taken in conjunction with the accompanying drawings wherein:

rifice Fig. l is a plan view of a line-above-ground type of transmission line with two tuners associated therewith in spaced relation along the line; and

Figs. 2 and 3 are cross-sectional views taken along lines 2-2 and 3 3, respectively, of Fig. l.

Referring to the drawings, the transmission line comprises a first conductor 1 and a second or line conductor 2 spaced apart by a thin strip or layer of dielectric material 3. The two conductors 1 and 2 are preferably of iiat strip form, the rst conductor being wider than the line conductor so as to present a planar surface with respect thereto for propagation of microwave energy along the line in a mode similar to the TEM pole. In the present embodiment, the dielectric strip 3 is shown to be wider than the planar conductor 1 to serve as additional support for the tuner. The dielectric material may be of polystyrene, polyethylene, Teflon, fiberglass or laminated fiberglass impregnated with Teflon, quartz, or other suitable material of a high dielectric quality. The conductors, 1 and 2 may be formed on the dielectric strip by any of the known printed circuit techniques, one suitable method being an electrolytic etching process.

The dielectric strip 3 is provided with a recessed portion 4 of suicient length longitudinally of the line to provide for longitudinal adjustment of the tuner supported in the recess. The tuner comprises a dielectric strip 5 which is of a thickness to correspond substantially to the depth of the recess 4. Carried on the upper surface of the dielectric strip S are two network conductors 6 and 7 which extend beyond the edge of the strip 5 for overlapping engagement with the line conductor 2, as indicated at 8 and 9, Figs. l and 3. The spacing ofthe conductors 6 and 7 in the embodiment illustrated is chosen to comprise substantially `the width of the conductor Z, although a wider or narrower spacing may be employed. The strip 5 is provided with a dovetailed recess 10 which receives -a dielectric strip 11 having on its surface a conductor 12 adapted to couple together the two conductors 6 and 7. The strip 11 together with the conductor 12 is adjustable lengthwise of the conductors 6 and 7 so as to provide an adjustable resonant loop network which comprises in conjunction with the planar surface of conductor 1 a section of the line conductor 2 between the points 8 and 9, sections of conductors 6 and 7 and the interconnecting conductor 12. By adjusting the position of conductor 12 the size of the resonant network may be changed thereby providing for selective tuning over a band of frequencies.

While the conductor 12 is the only conductor of the network of conductors shown for independent adjustment, it will be clear to those skilled in the art that one or both of the conductors 6 and 7 could be adjusted relative to each other within limits to also obtain a change in the size ofthe resonant network, the conductor 12 in that case being of the necessary width or in overlapping relation with respect to conductors 6 and 7 to provide satsfactory coupling for such adjustment. It will also be apparent to those skilled in the art that the conductors 6 and 7 could abut the side edge of conductor 2, although an overlap is tobe preferred for good coupling.

Additional tuners ysuch as the one indicated at 14 may be provided in tandem relation to the one described. kIn order to provide for adjustment of such tuners relative to each other along the line 2, the dielectricvstrip 3 is provided with slots as indicated at 15 and 16 through which guiding stubs 17 and 18 extend from the dielectric piece 5. This'arrangement provides for adjustment of the tuner lengthwise of thevline throughout the length of the recess 4. A plurality of such tuners arranged in tandem relation along the transmission line may be ad p justed for operation as a band pass lter. A single tuner may be employed for impedance matching purposes by locating it adjacent a junction or other devices coupled to the transmission line.

A single tuner, by way of example, has been constructed and found to operate with the following characteristicS. The width of the line conductor 2, as well as conductors 6, 7 and 12, was .22 and the spacing of the dielectric 3 between the conductors 1 and 2 was 1/16 of an inch. Assuming that microwave energy is applied at one end of the transmission line as indicated by the arrow 19, the other end being suitably loaded, it was found that the conductor 12 could be adjusted so that the output power of the line was varied between a maximum and zero. It was also found that the input Voltage standing wave ratio was varied from a low of 1.4 to a high of approximately 8. By maintaining the conductor 12 in a fixed position, movement of the tuner longitudinally of the line 2 showed only a slight variation in the output power and the voltage standing wave ratio remained substantially constant. These tests were made over a frequency band of 4575 to 4825 mcs/sec.

It will be understood, of course, that the proportions of the network formed by the conductors 6, 7 and coupling conductor 12, as well as the relative positions thereof and the spacing relative to conductor 1 may be modified; also that the width of conductors 6 and 7, and also 12 may be quite different from the width of conductor 2. It should also be understood that the dielectric strip 3 may be the same width as the planar conductor 1 if desired and the conductor pieces 6, 7 and 12 may be made integral with the line conductor 2 fora fixed resonant network once a particular proportion has been determined for a given application. Such a printed network would be formed from predetermined design during the etching process of the line conductor 2.

While we have described above the principles of our invention in connection with specific apparatus, it is to be clearly understood that this description is made by way of example only and not as a limitation to the scope of our invention, as set forth in the objects thereof and in the accompanying claims.

We claim:

1. A tuner for a microwave transmission line of the type comprising a first conductor, a second conductor and dielectric means spacing said conductors in substantially parallel relation, said first conductor being wider than said second conductor so that said first conductor presents substantially a planar surface with respect to said second conductor; said tuner comprising a pair of conductors disposed in spaced parallel relation to each other and to said first conductor, said pair of conductors being coupled to said second conductor and conductive means couplingr together said pair of conductors at a distance from said second conductor to form in conjunction with the planar surface of said first conductor a resonant network.

2. A tuner according to claim l, further including means supporting said conductive means for adjustment whereby the size of said resonant network may be varied.

3. A tuner according to clairn 1, wherein said dielectric means comprises a layer of dielectric material overlying said first conductor and supporting said pair of conductors.

4. A tuner according to claim 3, wherein said layer of dielectric material has a recess in the surface thereof adjacent said second conductor and dielectric means received in said recess to support said pair of conductors for adjustment relative said second conductor.

5. A tuner according to claim 3, wherein said conductive means includes a coupling conductor disposed between said pair of conductors and means supporting said coupling conductor for movement lengthwise along said pair of conductors.

6. In combination, a first conductor presenting a planar surface, a layer of dielectric material disposed over said planar surface, a second conductor narrow in width compared to said planar conductor and carried by said dielectric layer in substantially parallel spaced relation to said planar surface, said first and second conductors forming a transmission line over which microwave energy may be propagated, a pair of network conductors disposed at right angles to said second conductor in coupled relation therewith and in substantially parallel spaced relation to said planar surface, and a third network conductor coupling together said pair of network conductors at a distance from said second conductors to form a resonant network.

7. A combination according to claim 6, wherein one of said network conductors is movable relative to the other network conductors whereby the size of said resonant network may be changed.

S. A combination according to claim 6, wherein said pair of network conductors each comprises a relatively short length conductor and said third network conductor comprises a conductor spanning the space between said short length conductors with means for moving it longitudinally of said short length conductors.

9. A combination according to claim 6, wherein said layer of dielectric material is provided with a recess in the upper surface thereof adjacent said second conductor and a strip of dielectric material is received in said recess to support said network conductors.

l0. A combination according to claim 9, wherein said layer of dielectric material and said strip of dielectric are provided with coactive means for guiding said strip of dielectric for movement longitudinally of said second conductor.

1l. A kcombination according to claim 9, wherein said strip of dielectric material includes a recess disposed at right angles to said second conductor and means received in said last mentioned recess for guiding said third network conductor for adjustment relative to said second conductor.

12. A combination according to claim 6, further in cluding in spaced relation to said first mentioned resonant network, a second pair of network conductors disposed in parallel relation to each other and to said planar conductor and at right angles to said second conductor, and a network conductor disposed in coupling relation with said second pair of network conductors to form in conjunction with said second conductor a second resonant network.

13. A combination according to claim l2, further including a dielectric strip supporting the conductors of said second resonant network, said strip and said layer of dielectric material being provided with coactive means whereby said second resonant network is adjustable relative to the first recited resonant network.

14. in combination with a transmission line of the type comprising a first conductor, a second conductor and dielectric means spacing said conductors in substantially parallel relation, said rst conductor being wider than said second conductor so that said first conductor presents substantially a planar surface with respect to said second conductor; a plurality of tuning networks disposed in tandem relation along said line, each of said tuning networks comprising a pair of parallel conductors with one end of the pair coupled to said second conductor, said pair of conductors being disposed in a plane parallel to said first conductor and conductive means coupling together said pair a distance from said second conductor.

Etched Sheets Serve as Microwave Components, by R. M. Barrett; Electronics; June 1952; pages 114-118. 

